A very small dog, usually less than 10 or 15 pounds, usually short-haired but not always. Usually not of much practical use as a watchdog or protector, but kept mainly as a companion by little old ladies, gay men who don't like cats, and Paris Hilton. Includes such breeds as the Chihuahua, the Miniature Pinscher, the Rat Terrier and other similarly sized breeds.

"That rat dog is 3 years old and he isn't housebroken YET?"

"I swear, if that rat dog tries to bite me again, I'll stuff him in a sock and hang him up as cat bait!"